This invention relates to a process for converting a solution of solidifiable polymer in a volatilizable solvent into a plurality of essentially spheroidal granules.
It is well known in the art that various liquid foodstuffs such as milk, eggs, orange juice, and coffee, etc. can be spray dried by steam or hot air. In U.S. Pat. No. 3,039,107, dated 6-12-62, there is disclosed a method wherein these dried food products are agglomerated by contact with a spray of the untreated liquid food.
It is further known from the following patents that polymeric particulates and/or granules in water slurries can be produced from organic slurries or solutions of various polymers with steam precipitation:
U.S. Pat. No. 2,592,814 (4-15-52) PA1 U.S. Pat. No. 3,050,113 (8-21-62) PA1 U.S. Pat. No. 3,202,647 (8-24-65) PA1 U.S. Pat. No. 3,287,301 (11-22-66) PA1 U.S. Pat. No. 3,306,342 (2-28-66) PA1 U.S. Pat. No. 3,427,370 (2-11-69) PA1 U.S. Pat. No. 3,450,184 (6-17-69) PA1 U.S. Pat. No. 3,596,700 (8-3-71) PA1 U.S. Pat. No. 3,862,103 (1-21-75) PA1 U.S. Pat. No. 3,508,339 (4-28-70) PA1 U.S. Pat. No. 3,804,145 (4-16-74) PA1 U.S. Pat. No. 3,968,003 (7-6-76) PA1 U.S. Pat. No. 4,209,912 (7-1-80) PA1 U.S. Pat. No. 4,212,967 (7-15-80)
The following patents show that it is known to produce dry or substantially dry polymeric granules from polymer solutions with steam precipitation:
In addition to the foregoing, it is known from U.S. Pat. No. 4,252,968 (2-24-81) that polycarbonate powders prepared in U.S. Pat. No. 4,212,967 can be agglomerated in a stirred and heated tubular drier wherein the powders are heated to 165.degree.-190.degree. C.
While the above preparation of polymer granules in water slurries appears to be effective, it is a distinct disadvantage to subsequently separate out the water and remove the residual water absorbed therein. Furthermore, it is a distinct disadvantage in U.S. Pat. No. 4,252,968 to make polymer powders and subsequently agglomerate these in a rotating mechanical device which has the possibility of mechanical breakdowns.